![]() However, there is concern that the spatial and contrast resolution afforded by SPECT/CT may not be adequate for scanning of the small joints, such as those of the wrist and hand, that are affected earlier in the RA disease process. The acquisition of dual-phase SPECT/CT could provide insight into RA disease activity in the small joints. Only a few studies have utilized scanning at multiple timepoints ( 12) or used three-dimensional acquisition techniques ( 13- 15). Most of the published studies to date employing scintigraphy in RA patients used a single delayed osseous phase scan, in planar, two-dimensional acquisition mode ( 10, 11). Soft-tissue phase images acquired shortly after tracer injection reflects local blood flow and soft tissue vascularity, which typically are increased during inflammation ( 8) while the delayed osseous phase (3–4 h after injection) is reflective of osteoblastic response ( 9). Skeletal scintigraphy using diphosphonate radiotracers has been used for assessing inflammatory arthritis ( 6, 7). The changes in the status of synovial vascularity and bone metabolism are known to typically precede anatomical changes therefore, non-invasive imaging tools capable of quantifying these processes may offer unique opportunity for RA disease activity evaluation and risk stratification ( 5). This has been designated as the outside-in hypothesis, in contrast to the inside-out hypothesis, which postulates that joint inflammation originates in the bone marrow ( 4). Additionally, synovitis may stimulate osteoclastic differentiation with subsequent cortical bone resorption and breach of the synovium/bone marrow barrier ( 3). The inflamed synovial membrane may initiate and promote further invasion of cartilage and bone ( 2). Synovitis is the hallmark of Rheumatoid Arthritis (RA), and is typically characterized by leukocyte infiltration, hypervascularity, neoangiogenesis, synoviocyte proliferation and fibroblast activation ( 1). Keywords: Bone scan rheumatoid arthritis SPECT/CT soft tissue vascularity osteoblastic response SPECT/CT may provide a unique means for assessing both synovitis and osseous involvement in RA joints using the same radiotracer injection. Intra-observer agreement for qualitative SPECT findings was substantial for both the soft-tissue phase (kappa =0.78, 95% CI: 0.72–0.83) and osseous-phase (kappa =0.70, 95% CI: 0.64–0.76) scans.Ĭonclusions: Extracting reliable quantitative and qualitative measures from dual-phase 99mTc-MDP SPECT/CT hand scans is feasible in RA patients. Intraclass Correlation Coefficient (ICC) for MCCR was excellent. The MCCR from soft-tissue phase scans was significantly higher for clinically abnormal joints compared to clinically normal ones P<0.001, however the MCCR from the osseous phase scans were not different between the two joint groups. A total of 280 joints (20 per hand) were evaluated. Results: Four participants completed seven studies (all four were imaged at baseline, and three of them at follow-up after 1-month of arthritis therapy). Qualitative and quantitative evaluations were repeated to assess reliability. Joints were evaluated qualitatively (normal vs. ![]() ![]() Methods: A SPECT/CT imaging protocol was developed in this pilot study to scan both hands simultaneously in participants with RA, in two phases of 99mTc-MDP radiotracer uptake, namely the soft-tissue blood pool phase (within 15 minutes after radiotracer injection) and osseous phase (after 3 hours). Policy of Dealing with Allegations of Research Misconductīackground: To prospectively demonstrate the feasibility of performing dual-phase SPECT/CT for the assessment of the small joints of the hands of rheumatoid arthritis (RA) patients, and to evaluate the reliability of the quantitative and qualitative measures derived from the resulting images.Policy of Screening for Plagiarism Process.
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